Why Aren’t All People Beautiful?

Maybe the genes that make hot males make distinctly un-hot females.

Natural selection, we’re told, is the process by which nature promotes our best qualities. But a look around strains that notion. If nature selects health, beauty, and intelligence, why are most of us far from flawless?

It may be because genes involved in reproduction work against themselves in opposite sexes across generations, says biologist Katharina Foerster at the University of Edinburgh. In her study of eight generations of red deer in Scotland, she noticed a curious pattern: The most prolific male deer sired daughters that tended to have fewer offspring, while the worst male breeders (the deer equivalent of ugly) fathered females that had more offspring. This is evidence, Foerster says, of sexually antagonistic genes. The same gene that makes a buck sexually successful can leave his daughter behind.

Foerster suspects that sexual antagonism is a way to maintain genetic diversity. But with so many reproductive choices available, it would be nearly impossible to detect this pattern in humans.